JP2016150969A - Adhesive-containing silica microcapsule and method for the production thereof, adhesive material and adhesive material applicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique whereby an adhesive is contained inside a fine particle and the fine particle is destructed to express adhesive performance.SOLUTION: An adhesive-containing silica microcapsule is obtained by containing an adhesive in a silica microcapsule which can be destructed by external force.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive-containing silica microcapsule, a method for producing the same, an adhesive material, and an adhesive material applicator.

  Techniques for expressing the adhesive performance of an adhesive are required in various fields. In the field of stationery, when stickers are pasted with glue, tape, etc., there is no stickiness at the stage of applying an adhesive to one paper, and stickiness is manifested only when the other paper is stacked. This increases user comfort. In order to bring such a function to the pressure-sensitive adhesive, various methods have been proposed, and one of them is a pressure-sensitive pressure-sensitive adhesive. As a representative method, many researches have been conducted on the technology to exert adhesive performance by encapsulating an adhesive and related drugs in a capsule-like material and releasing the contained adhesive by pressurizing and destroying the capsule material. Has been. For example, in pressure sensitive adhesives and pressure sensitive adhesive sheets, there are those in which the pressure sensitive adhesive is encapsulated in a synthetic resin such as vinylidene chloride / acrylonitrile copolymer, polyvinyl alcohol, melamine / formaldehyde resin, isocyanate resin, etc. depending on the purpose (patent) Reference 1). In addition, there are pressure-sensitive adhesives and pressure-sensitive adhesive sheets using a combination of a pressure-breaking microcapsule and a heat-breaking microcapsule using gelatin-gum arabic and other proteins, polysaccharides, PVA (polyvinyl alcohol), and the like (Patent Literature). 2). There is also a pressure-sensitive adhesive in which a water-based adhesive is enclosed in urethane resin, phenol formaldehyde resin, styrene resin, and acrylic resin microcapsules using a W / O / W emulsion (Patent Documents 3 and 4). There is also a technique in which a cross-linking agent or a pressure-sensitive adhesive that causes a cross-linking reaction is encapsulated in a microcapsule and a cross-linking reaction is performed only at a necessary place through destruction of the microcapsule to reduce a transfer mistake (Patent Document 5). A resin composition in which a plasticizer or a capsule-type particle containing a plasticizer and a tackifier is mixed with a normal pressure-sensitive adhesive, and by making the particle diameter of the capsule-type particle equal to the sheet material thickness, There is also an example of synthesizing a pressure sensitive adhesive sheet material that has been destroyed by the shell and has not been tacky until then, and that has been cross-linked with acrylic acid, acrylonitrile, etc. as a capsule material. (Patent Document 6).

  There is also an example in which a release agent is added in the microcapsule instead of an adhesive, and the release agent is released by breaking the microcapsule. For example, those using microcapsules made of synthetic polymers such as starch, polyvinylpyrrolidone, carboxymethylcellulose, gelatin, etc. (Patent Document 7), and synthetic resins such as melamine / formaldehyde resin and isocyanate resin as wall film agents A pressure-sensitive adhesive sheet (Patent Document 8) or the like provided with re-adhesion performance by being encapsulated in a microcapsule. Since these capsule materials and microcapsule materials are synthesized by a coacervation method, an interfacial polymerization method, an in-situ polymerization method, etc., the capsule structure of the core inclusion and the coating capsule material is built simultaneously. However, there is also an example in which a hollow and non-sticky synthetic resin microcapsule without a core substance is filled with a pressure-sensitive adhesive (Patent Document 9). Most of the capsules and microcapsules exemplified in these examples use polymer organic substances, and examples using inorganic materials such as silica include silica as a pigment to be encapsulated, not as a capsule material. There is only an example using (Patent Document 10).

  On the other hand, research using silica or silicate compounds as capsule materials has been progressing rapidly in recent years. As a method that has been actively studied recently, there is a method using a core-shell material (Non-patent Document 1). As a typical example, polystyrene nanoparticles are used as a core material / core material, and silica is precipitated around the core material using a sol-gel method to synthesize a core-shell type material once. Thereafter, many methods for producing silica hollow particles and microcapsules by removing the core polystyrene by baking or the like have been reported (Non-Patent Documents 2 and 3). By applying this technique, there is an example of fine particles in which the shell containing silicone oil is silica (Patent Document 11). On the other hand, a method of synthesizing silica hollow particles / microcapsules without using a core substance has also been reported (Non-patent Document 4, Patent Documents 12 and 13). In this method, it is possible to incorporate other substances into the capsule at the same time as the preparation of the microcapsule material, and there are examples in which a biopolymer material such as protein is encapsulated (Patent Document 14, Non-Patent Document 5). However, in this method, since the substance to be encapsulated is mixed in the water glass aqueous solution, it is difficult to encapsulate a hydrophobic material that is not dissolved in water or distributed to water.

  As mentioned above, only organic materials such as polymers are used as the material for encapsulating the adhesive. However, when used for general stationery, there is a concern about the effects of monomers remaining during production on the human body. The As a material for capsules and microcapsules, it is particularly important to use silica, which has little adverse effect on the human body and has high environmental compatibility, from the viewpoint of use and spread of the material for adhesive stationery. However, in spite of such practical advantages of silica, a silica capsule / microcapsule containing a pressure-sensitive adhesive or an adhesive has not been known so far.

JP2009-221346 JP2008-248065 JP2005-232390 JP2005-22023 JP 07-011211 JP 06-172725 JP2008-292873 JP 09-095650 JP 09-111203 A JP 09-099673 JP2013-000683 Patent 4997395 JP2010-053200 Patent No. 5051490

Y. Li, J. Shi, Adv. Mater., 26, 3176-3205 (2014) W. Leng, M. Chen, S. Zhou, L. Wu, Langmuir, 26, 14271-14275 (2010) M. Chen, L. Wu, S. Zhou, B. You, Adv. Mater., 18, 801-806 (2006) M. Fujiwara, K. Shiokawa, Y. Tanaka, Y. Nakahara, Chem. Mater., 16, 5420-5426 (2004) J. Biomed. Mater. Res. A, 81, 103-112 (2007)

  An object of the present invention is to provide a technique for synthesizing composite fine particles containing a pressure-sensitive adhesive inside fine particles and whose shell is made of silica, and a technology for expressing pressure-sensitive adhesive performance by breaking the fine particles.

  The present inventor made an emulsion of adhesive polymer in water by interfacial polymerization, etc., hydrolyzed and condensed the alkoxysilane compound, which is the raw material of silica, with an alkaline catalyst, and precipitated silica on the adhesive polymer emulsion By doing so, the adhesive-encapsulated silica composite particles were successfully synthesized. The reaction that causes hydrolysis and condensation reaction of an alkoxysilane compound with an alkaline catalyst is known as the Stover method (W. Stober, A. Fink, J. Colloid Interface Sci., 26, 62-69 (1968)), and the particle size is 100 nm. The following silica nanoparticles are known to precipitate. Since the silica nanoparticles can densely coat the emulsion of the pressure-sensitive adhesive polymer, the pressure-sensitive adhesive is not exposed to the outside of the microcapsules as it is, and does not have adhesive performance. By exposing to the outside of the microcapsule, the adhesive performance was successfully developed, leading to the present invention (FIGS. 1 and 2).

The present invention provides the following pressure-sensitive adhesive-encapsulated silica microcapsules, a method for producing the same, an adhesive material, and an adhesive material applicator.
Item 1. A pressure-sensitive adhesive-encapsulated silica microcapsule comprising a pressure-sensitive adhesive encapsulated by a silica microcapsule that can be broken by an external force.
Item 2. Item 2. The pressure-sensitive adhesive-encapsulated silica microcapsule according to item 1, wherein the silica microcapsule has a thickness of 0.5 to 50 µm.
Item 3. Item 3. The pressure-sensitive adhesive-encapsulated silica microcapsule according to Item 1 or 2, wherein the ratio of the thickness of the silica microcapsule to the total particle size of the silica microcapsule is 1 to 30%.
Item 4. The adhesive material formed by disperse | distributing the adhesive inclusion | inner_cover silica microcapsule of any one of claim | item 1 -3 to ethanol.
Item 5. An adhesive material applicator comprising a main body including a storage chamber for storing the adhesive material according to Item 4, and a nozzle for guiding the adhesive material in the storage chamber to the outside little by little.
Item 6. A surfactant and an alkoxysilane are added to an aqueous emulsion of a pressure-sensitive adhesive polymer, and the hydrolysis and condensation reaction of the alkoxysilane is caused in the presence of an alkaline catalyst to precipitate silica on the pressure-sensitive adhesive polymer emulsion. A method for producing a pressure-sensitive adhesive-encapsulated silica microcapsule comprising a pressure-sensitive adhesive encapsulated by a silica microcapsule that can be broken by an external force.
Item 7. Item 7. The method for producing pressure-sensitive adhesive-containing silica microcapsules according to Item 6, wherein a surfactant is further added to the aqueous emulsion.

  The pressure-sensitive adhesive-encapsulated silica microcapsule of the present invention is suitable as an adhesive material because it exhibits tackiness only after breaking the silica microcapsule. This adhesive material is applied to an envelope or the like with an adhesive material applicator, and the silica microcapsules are broken by pressing and overlapping the paper, so that the adhesive performance is exhibited.

Conceptual diagram of silica-coated adhesive polymer production Conceptual diagram of pressure-sensitive adhesive appearance of silica-coated pressure-sensitive adhesive polymer Example of silica nanoparticles coated on the adhesive emulsion surface Infrared spectrum of pressure sensitive adhesive-encapsulated silica microcapsules Electron microscope image of pressure-sensitive adhesive-encapsulated silica microcapsules Infrared spectrum of pressure sensitive adhesive-encapsulated silica microcapsules

  An aqueous emulsion of the pressure-sensitive adhesive polymer with water may be prepared by a usual suspension polymerization method or the like. The pressure-sensitive adhesive polymer in the aqueous emulsion is not particularly limited as long as it does not dissolve in water and has sufficient pressure-sensitive adhesive performance. Rubber pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, urethane pressure-sensitive adhesive, and silicone-based pressure-sensitive adhesive And vinyl ether adhesives, and acrylic adhesives are preferred. As an acrylic adhesive, (meth) acrylic acid ester, more specifically, (meth) ethyl acrylate, (meth) acrylate i-propyl, (meth) acrylate butyl, (meth) acrylate i-butyl , 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isomyristyl (meth) acrylate, methoxyethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, ( Examples include (meth) acrylic acid esters such as lauryl (meth) acrylate and dimethylaminoethyl (meth) acrylate. These can be used alone or in combination of two or more. Further, these base polymers may be copolymerized with an acrylic ester having a hydroxyl group to adjust the adhesive properties and hydrophilicity. Examples of the ester having a hydroxyl group to be copolymerized with the base polymer include hydroxyethyl (meth) acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and the like. These may be used alone or in combination of two or more. Can be used. In particular, it is preferable to use a copolymer of 2-ethylhexyl acrylate and 2-hydroxypropyl acrylate from the viewpoint of adhesion performance and easy procurement. The size of the emulsion at that time is not particularly limited, but it is easy to control the expression of pressure-sensitive adhesive by encapsulating the pressure-sensitive adhesive, and to develop sufficient pressure-sensitive adhesive force for adhesion of adherends such as paper. 1-100 μm is preferable, and 20-80 μm is more preferable. This emulsion may be used after being separated from water once by filtration or the like, but it may be used as it is, and the form of use is not particularly limited as long as the emulsion state is maintained.

  This adhesive emulsion is mixed with a surfactant. A surfactant is usually added at the time of suspension polymerization, and an additional surfactant is not essential, but is preferably added in order to improve the stability of the emulsion during the silica coating reaction. The surfactant in this case is not particularly limited as long as it sufficiently stabilizes the emulsion, but a sorbitan surfactant called Span or Tween is preferable. The type is not particularly limited, but the surfactant has a moderate HLB value, preferably a value of about 2 to 10, more preferably 2.5 to 8, more preferably 3 to 7. is there. However, the surfactant to be used is appropriately selected depending on the type of the pressure-sensitive adhesive polymer and the like in order to stabilize the emulsion of the pressure-sensitive adhesive polymer. An example of a surfactant exhibiting good results when the pressure-sensitive adhesive polymer is a copolymer of 2-ethylhexyl acrylate and 2-hydroxypropyl acrylate is Span80 (HLB value: 4.3). The addition amount is not particularly limited as long as the emulsion is stabilized, but it is preferably 2 to 20% by mass, more preferably 5 to 15% by mass with respect to the pressure-sensitive adhesive polymer in the emulsion. After this emulsion is agitated and fully blended, further ion-exchanged water is added. The amount of water is not particularly limited as long as the emulsion is stabilized, but is preferably about 50 to 200% by mass, more preferably about 75 to 150% by mass with respect to the adhesive emulsion. Thereafter, an alkaline catalyst serving as a catalyst for condensation of the silane compound is added. Although it does not specifically limit as this catalyst, Ammonia water can be illustrated. The amount to be added is not particularly limited as long as the silane compound is satisfactorily hydrolyzed and condensed. In the case of aqueous ammonia, the reagent concentration is not particularly limited. The amount of ammonia in the total reaction solution in the ammonia water addition stage is preferably about 1 to 10% by mass, more preferably about 2 to 8% by mass.

  Thereafter, after sufficiently stirring, an alkoxysilane serving as a silica source is added. The alkoxysilane is not particularly limited as long as it can satisfactorily coat silica, but examples include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraphenoxysilane, and the like alone or Can be used in a mixture. If silica particles can be deposited and coated satisfactorily, an organic alkoxysilane such as methyltriethoxysilane or ethyltriethoxysilane may be further added. The amount of alkoxysilane added is not particularly limited as long as the silica can be satisfactorily coated, but is preferably about 0.5 to 10 mmol, more preferably about 1 to 5 mmol, with respect to 1 g of the pressure-sensitive adhesive polymer. When the amount of this alkoxysilane is large, the silica can be coated sufficiently, but the adhesive amount in the adhesive-encapsulated capsule may decrease and the adhesive performance may deteriorate, so adjust the adhesive strength of the adhesive to be coated. is necessary. The order of adding the surfactant, catalyst, and alkoxysilane added to the pressure-sensitive adhesive polymer emulsion liquid is not particularly limited, but the alkoxysilane is preferably the last because it is precipitated as silica nanoparticles. The mixture thus obtained is heated to precipitate silica. As reaction conditions, 20-90 degreeC is good, More preferably, 40-80 degreeC is good. Although reaction time will not be specifically limited if silica precipitation occurs, 1 to 20 hours are good, More preferably, it is 2 to 10 hours. The silica-coated pressure-sensitive adhesive suspension thus prepared can be added to a lower alcohol such as ethanol to form an adhesive material. Since the adhesive does not substantially dissolve in the lower alcohol, the dispersion of the lower alcohol has a free-flowing property. When applied to an adherend such as paper, the lower alcohol evaporates quickly, and the adhesive-encapsulated silica microcapsules It remains on the adherend. The silica microcapsules are broken by applying pressure from above the adherend such as paper, whereby the adhesive is released and the adherend is bonded. As the lower alcohol, ethanol is particularly preferred. Methanol, isopropanol, or a mixture thereof may be used in place of ethanol, but the selection of the solvent may be performed in consideration of regulations when actually used. FIG. 3 shows an electron microscopic image of the silica-coated fine particles that can be synthesized in this way, and it can be seen that silica nanoparticles having a size of about 100 nm are formed. The amount of ethanol is preferably excessive with respect to the suspension, and is usually 2 to 20 times by mass, more preferably 5 to 15 times. At that time, an additive may be added to this ethanol. For example, ethanol added with polyvinylpyrrolidone may be used. In order to improve the performance of the particles, polyvinylpyrrolidone is added in an amount of 0.1 to 5% by mass with respect to ethanol. More preferably, 0.2 to 2% by mass is added. This ethanol solution is thoroughly blended by stirring for about 1 to 5 hours. The capsule particles of the pressure-sensitive adhesive thus obtained may be separated from the solution by filtration, centrifugation, etc., but when considering application to paper or the like, a thick suspension from which the supernatant of the ethanol solution has been removed A liquid may be used.

  The average particle size of the silica-coated pressure-sensitive adhesive emulsion thus obtained is about 30 to 800 μm, preferably about 50 to 600 μm, more preferably about 70 to 400 μm, and particularly about 100 to 300 μm. The thickness of the silica layer of the silica microcapsule is about 0.5 to 50 μm, preferably 1 to 30 μm, more preferably 1 to 20 μm. The ratio of the thickness of the coated silica to the total particle size of the silica microcapsules is about 1 to 30%, preferably about 2 to 20%. For example, the average particle size of the silica microcapsules of FIG. 3 is about 150 μm, and the thickness of the coated silica layer is 2 to 10 μm. The ratio of the coated silica thickness to the total particle size of the silica-coated adhesive emulsion is about 2.5-12%.

  The pressure-sensitive adhesive emulsion-coated silica microcapsule thus obtained develops pressure-sensitive adhesiveness by being developed on an adherend such as paper and loaded from above. There are no particular restrictions on the materials to be developed such as paper, but ordinary copy paper, coated paper, high quality paper, Kent paper, matte coated paper, glossy paper, vinyl film materials such as polystyrene, polyethylene, and polypropylene, paper and polymer Examples include synthetic paper combined with a film. Although the load from the upper part for expressing adhesiveness is not specifically limited, 20 kPa-200 kPa is good, More preferably, it is 50-150 kPa. The peel resistance of the adhesive thus adhered is about 1 to 5 N / cm. This adhesive performance varies depending on the purpose of the product, for example, temporary adhesive performance such as a sticky note or strong adhesive performance such as adhesive sticking to a sealed letter, and is not particularly limited. It can be adjusted by stickiness or silica coverage.

  An adhesive material made of a suspension of lower alcohol, especially ethanol, in silica microcapsules is housed in a storage chamber of the applicator main body, and the adhesive material is led out from the nozzle provided in the applicator main body to the outside little by little to cover an object such as paper The adherend can be bonded by applying to the adhesive and applying a load from above to break the silica microcapsules.

  The adhesive material applicator of the present invention has, for example, a cylindrical shape including a main body having an adhesive material storage chamber and a nozzle for guiding the adhesive material in the storage chamber to the outside little by little. When the tip of the nozzle is pressed against an adherend such as paper, the adhesive material in the storage chamber is supplied to the adherend little by little through the nozzle.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.
Example 1 Preparation of silica nanoparticles coated on the surface of an adhesive emulsion-1
4. 100 g (0.542 mol) of 2-ethylhexyl acrylate, 25 g (0.192 mol) of 2-hydroxypropyl acrylate, and 1 g (0.003 mol) of 75% benzoyl peroxide are mixed thoroughly, and ammonium dodecyl sulfate as a surfactant. A solution obtained by mixing 21 g (0.044 mol) with 374 g of ion-exchanged water was stirred at 400 rpm for 30 minutes in a nitrogen atmosphere. Thereafter, the bath temperature was set to 68 ° C. using an oil bath, and the polymerization reaction was carried out with stirring for 5 hours after the reaction solution reached 65 ° C. After completion of the reaction, the reaction solution was allowed to cool. The particle size of the pressure-sensitive adhesive emulsion thus obtained was several tens to several hundreds μm, and the average particle size was about 150 μm. By changing the stirring speed, the average particle diameter can be controlled to a certain extent in the range of 100 to 300 μm. For example, the particle diameter can be reduced by increasing the stirring speed.

40 mL of the pressure-sensitive adhesive emulsion thus obtained (pressure-sensitive adhesive amount, about 10 g) was mixed with 1 g of surfactant Span 80 and stirred for several minutes, and then 50 mL of ion-exchanged water was added and further stirred for 5 minutes. Thereafter, 30 mL of 25% aqueous ammonia was added and stirred for 5 minutes, 3.00 g (19.71 mmol) of tetramethoxysilane (TMOS) was added, and the emulsion was stirred in a water bath at 75 ° C. for 6 hours. Thereafter, this emulsion was added to 1.2 L of ethanol and stirred for 1 hour, and then allowed to stand. At this time, 0.5 to 1.5% by weight of polyvinylpyrrolidone with respect to ethanol was previously added. After standing still sufficiently, the transparent supernatant was removed to obtain a silica microcapsule-containing pressure-sensitive adhesive. The amount of the pressure-sensitive adhesive in the microcapsules thus obtained was 89.90% based on the result of weight loss of 200 to 600 ° C. in thermal analysis. From the infrared spectrum shown in Figure 4, the fine particles was found that absorption of 473cm ^-1 absorption and silica derived from carbonyl 1736 cm ^-1 derived from the pressure-sensitive adhesive polymer is a composite of both can be observed. Further, as shown in FIG. 5, the particles are coated with silica nanoparticles (right) around an adhesive emulsion (left) of about 50 microns.
Example 2 Evaluation of Adhesive Properties of Silica Nanoparticles Coated on the Surface of the Adhesive Emulsion The performance of the adhesive emulsion coated with the silica nanoparticles obtained in Example 1 was measured by the following method.

First, evaluation was performed on the expression of tack of each sample.
(1) 3 mg of the sample prepared in Example 1 was set on a copy paper strip (KB39N: KOKUYO, 297 mm × 50 mm, about 1 g). This sample was strip-shaped and became a lump with a diameter of about 2 mm.
(2) Put a strip on the same copy paper from above the set sample, and put a test jig (about 200g) with a contact area of 1cm ² for 3 seconds, pressurize at 19.6k Pa, and lift the covered strip Thus, the occurrence of tack at low load was confirmed. At this time, if the lower strips are lifted at the same time, it is considered as “tacked”.
(3) Using the same specimen as in (2), place a weight (approximately 1000 g) on a contact area of 1 cm ² for 3 seconds, pressurize at 98.0 kPa, and lift the covered strip. Tack expression was confirmed.
As a result of performing the measurement according to the above procedure, no tack was developed when pressurized at 19.6 kPa, but tack was confirmed when pressurized at 98.0 kPa.

Second, the adhesive strength was measured. This test was performed in accordance with JIS Z 0237-8 and by changing the test conditions and the like as appropriate.
(1) 0.1 g of the sample prepared in Example 1 was spread on a prescribed copy paper strip (KB39N: KOKUYO, 297 mm × 50 mm, about 1 g) so that the coating area was 10 mm wide × 100 cm.
(2) A similar copy paper strip was placed on the sample set in this manner, and a 1 kg weight rubber roller (diameter: 90 mm, thickness: 50 mm, butadiene styrene rubber with a thickness of about 2 mm was placed on the iron core. 1) was reciprocated twice at a speed of 50 mm / sec and pressurized.
(3) After pressurization, in normal condition (temperature 23 ° C, humidity 50%), cured for 40 minutes which is the optimum time by experiment, using autograph (AGS-X, manufactured by Shimadzu), 300mm / min The peel resistance was measured at a speed of. The measurement was carried out 5 times, and the average value of 5 maximum convex points on the measurement chart was taken as the measurement value.

  As a result of carrying out the measurement according to the above procedure, the peel resistance of the sample was about 1.7 N / cm. This adhesive performance was almost the same as the case where a small tape glue (T-D470-07) manufactured by KOKUYO S & T was evaluated by the same method.

Based on the above results, the pressure-sensitive adhesive emulsion coated with silica nanoparticles does not have adhesiveness under low load, but the adhesiveness is expressed by being crushed by the pressure of 98.0 kPa and the internal adhesive protruding. It was confirmed to be a microcapsule.
Example 3 Preparation of silica nanoparticles coated on the surface of an adhesive emulsion-2
In the same manner as in Example 1, 4.11 g (19.71 mmol) of tetraethoxysilane (TEOS) was used instead of tetramethoxysilane, and pressure-sensitive adhesive-encapsulated silica microcapsules were synthesized in the same manner. The adhesion performance was performed in the same manner as in Example 1. The amount of the pressure-sensitive adhesive in the microcapsules thus obtained was 88.33% from the result of the weight loss of 200 to 600 ° C. in the thermal analysis. From FIG. 6, it was found that the fine particles contained an adhesive polymer and silica (left in FIG. 6), and an emulsion of about 50 microns was coated on silica from the electron microscopic image (right in FIG. 6).

  When the performance of the pressure-sensitive adhesive emulsion coated with the silica nanoparticles was measured in the same manner as in Example 1, no tack was exhibited when pressurized to 19.6 kPa, but the occurrence of tack was confirmed when pressurized to 98.0 kPa. It was done. In addition, the adhesive strength when pressurized using a 1 kg rubber roller is 1.5 N / cm, and the sample manufactured using TEOS does not have adhesiveness under low load, but the pressure is 98.0 kPa. The adhesiveness was expressed by being crushed by the internal pressure and the internal adhesive protruding.

  The present invention provides a material that expresses the adhesive performance of an adhesive by using a physical action of pressurization as a trigger. For example, it can be applied to work in which a gluing process and an assembling process are performed separately. Specifically, when gluing a large number of envelopes, the first worker first develops the material on one side of the envelope, but at this time it is not sticky and does not stain hands, clothes, etc. . Subsequently, when the second worker encloses the document in the envelope, the inclusions are not soiled by the material developed in the envelope, and can be glued by a simple operation of pressing. , Work efficiency can be improved.

Claims (7)

A pressure-sensitive adhesive-encapsulated silica microcapsule comprising a pressure-sensitive adhesive encapsulated by a silica microcapsule that can be broken by an external force. The pressure-sensitive adhesive-encapsulated silica microcapsule according to claim 1, wherein the thickness of the silica microcapsule is 0.5 to 50 μm. The pressure-sensitive adhesive-encapsulated silica microcapsule according to claim 1 or 2, wherein the ratio of the thickness of the silica microcapsule to the total particle size of the silica microcapsule is 1 to 30%. The adhesive material formed by disperse | distributing the adhesive inclusion | inner_cover silica microcapsule of any one of Claims 1-3 to ethanol. An adhesive material applicator comprising a main body including a storage chamber for storing the adhesive material according to claim 4 and a nozzle for guiding the adhesive material in the storage chamber to the outside little by little. A surfactant and an alkoxysilane are added to an aqueous emulsion of a pressure-sensitive adhesive polymer, and the hydrolysis and condensation reaction of the alkoxysilane is caused in the presence of an alkaline catalyst to precipitate silica on the pressure-sensitive adhesive polymer emulsion. A method for producing a pressure-sensitive adhesive-encapsulated silica microcapsule comprising a pressure-sensitive adhesive encapsulated by silica microcapsules that can be broken by external force. The method for producing a pressure-sensitive adhesive-encapsulated silica microcapsule according to claim 6, wherein a surfactant is further added to the aqueous emulsion.